Method and apparatus for signal transmission and reception

Abstract

A method and modem for communicating serial input data over a transmission link. Serial input data is partitioned into parallel data elements prior to rotation by an invertible linear mapping. Resulting frames of parallel signal elements sequentially modulate a carrier, which is then transmitted over the link. After receipt of the modulated carrier from the link, the signal is demodulated and assembled into frames of parallel signal elements which are derotated by an inverse linear mapping. Thresholding the result of the inverse mapping recovers the parallel data elements, which are then re-assembled into serial output data. The linear mapping employs: 1) commuting rotation matrices for convolutionally rotating data vectors into signal vectors and vice-versa; 2) filter bank polyphase rotation matrices; or 3) computationally efficient multi-rate wavelet filter banks. Transmitter pre-emphasis places most of the information in lower baseband frequencies; complimentary de-emphasis occurs in the receiver. Logarithmic amplification of the baseband signal prior to carrier modulation improves modulation gain and transmit channel noise attenuation. Coefficients of the rotation matrix of the receiver are adaptively equalized to correct for transmission path distortion. FM double-side band is employed in systems requiring minimized cost and complexity. FM single-side band is employed in systems in which bandwidth reduction is desirable. AM is also employable.

What is claimed is: 
     
       1. A modem transmitter for communicating serial input data as a signal over a transmission link, said modem transmitter comprising: a partitioning element for receiving and partitioning said serial input data into a parallel data set;   a rotation element, comprising a rotation matrix, for providing an invertible, linear conversion of said parallel data set into a parallel signal set;   a modulator, in communication with said rotation element, for modulating a carrier with said parallel signal set; and   a transmitter element, in communication with said modulator, for transmitting said modulated carrier as said signal over said transmission link, wherein said parallel data set is a plurality of data coordinates,   said parallel signal set is a plurality of signal coordinates, and   said rotation element is operative for applying said rotation matrix to said olurality of data coordinates to produce said plurality of signal coordinates.     
     
     
       2. The modem transmitter according to claim 1, wherein: said parallel data set is a plurality of mutually-orthogonal data coordinates; and   said parallel signal set is a plurality of mutually-orthogonal signal coordinates.   
     
     
       3. The modem transmitter according to claim 1, wherein said rotation matrix further comprises a filter bank polyphase rotation matrix, said rotation element applying said polyphase rotation matrix to said parallel data set to produce said parallel signal set. 
     
     
       4. The modem transmitter according to claim 3, wherein said filter bank polyphase rotation matrix further comprises a multi-rate wavelet synthesizer filter-bank, said rotation element applying said multi-rate wavelet synthesizer filter-bank to said parallel data set to produce said parallel signal set. 
     
     
       5. The modem transmitter according to claim 1, further comprising a pre-emphasis element, in communication with said partitioning element, for providing non-linear pre-emphasis amplification to said parallel data set prior to introduction of said parallel data set into said rotation element, said pre-emphasis amplification including unequal distribution of bits from said serial input data among a plurality of parallel data sub-bands. 
     
     
       6. The modem transmitter according to claim 5, said non-linear pre-emphasis amplification further including bit-representation levels in each data sub-band, said bit-representation levels determined by the number of bits distributed to the respective data sub-band. 
     
     
       7. The modem transmitter according to claim 5, further comprising a memory element, wherein said non-linear pre-emphasis amplification is achieved using a look-up table stored within said memory element. 
     
     
       8. The modem transmitter according to claim 1, further comprising a compression element, in communication with said rotation element, for providing non-linear amplification of said parallel signal set. 
     
     
       9. The modem transmitter according to claim 8, wherein said non-linear amplification is logarithmic Mu-law amplification. 
     
     
       10. The modem transmitter according to claim 8, further comprising an associated memory element, wherein said non-linear amplification is achieved using a look-up table stored within said memory element. 
     
     
       11. The modem transmitter according to claim 8, further comprising: a de-rotation element, in communication with said compression element, for returning the amplified parallel signal set into an amplified parallel data set;   a pre-emphasis element, in communication with said de-rotation element, for providing non-linear pre-emphasis amplification to said amplified parallel data set, said non-linear pre-emphasis amplification including unequal distribution of bits from said amplified parallel data set among a plurality of parallel data sub-bands; and   a subsequent rotation element, in communication with said pre-emphasis element, for rotating the pre-emphasized parallel data set into a pre-emphasized parallel signal set.   
     
     
       12. The modem transmitter according to claim 1, wherein said modulator is an FM modulator. 
     
     
       13. The modem transmitter according to claim 12, wherein said FM modulator employs a Class C RF amplifier in lieu of a digital-to-analog converter. 
     
     
       14. The modem transmitter according to claim 1, wherein said modulator is an AM modulator. 
     
     
       15. A modem receiver for receiving a modulated signal from a transmission link and for providing serial output data, said modem receiver comprising: a receiver element for receiving said modulated signal from said transmission link and for providing a modulated, parallel signal set;   a demodulator, in communication with said receiver element, for demodulating said modulated, parallel signal set from a carrier;   an inverse rotation element, comprising a derotation matrix in communication with said demodulator, for receiving a demodulated parallel signal set from said demodulator and for providing an invertible, linear conversion of said parallel signal set into a parallel data set; and   an assembling element for receiving and assembling said parallel data set into said serial output data, wherein said parallel signal set is a plurality of signal coordinates,   said parallel data set is a plurality of data coordinates, and   said inverse rotation element is operative for applying said de-rotation matrix to said plurality of signal coordinates to produce said plurality of data coordinates.     
     
     
       16. The modem receiver according to claim 15, wherein: said parallel signal set is a plurality of mutually-orthogonal signal coordinates; and   said parallel data set is a plurality of mutually-orthogonal data coordinates.   
     
     
       17. The modem receiver according to claim 15, wherein said de-rotation matrix further comprises a filter bank polyphase rotation matrix, said inverse rotation element applying the polyphase rotation matrix to said parallel signal set to produce said parallel data set. 
     
     
       18. The modem receiver according to claim 17, wherein said filter bank polyphase rotation matrix further comprises a multi-rate wavelet analyzer filter-bank, said de-rotation element applying said multi-rate wavelet analyzer filter-bank to said parallel signal set to produce said parallel data set. 
     
     
       19. The modem receiver according to claim 15, further comprising a de-emphasis element, in communication with said inverse rotation element, for providing non-linear de-emphasis attenuation to said parallel data set prior to introduction of said parallel data set into said assembling element, said de-emphasis attenuation applied to an uneven distribution of bits among each of a plurality of parallel data sub-bands. 
     
     
       20. The modem receiver according to claim 19, further comprising an associated memory element, wherein said non-linear de-emphasis attenuation is achieved using a look-up table stored within said memory element. 
     
     
       21. The modem receiver according to claim 15, said assembling element recognizing integer bit-representation levels in said parallel data set and resolving actual parallel data set levels to the integer levels according to a predetermined rule. 
     
     
       22. The modem receiver according to claim 15, further comprising a decompression element, in communication with said inverse rotation element, for providing non-linear attenuation of said parallel signal set received from said receiver element. 
     
     
       23. The modem receiver according to claim 22, wherein said attenuation is logarithmic Mu-law attenuation. 
     
     
       24. The modem receiver according to claim 22, further comprising a memory element, and wherein said non-linear attenuation is achieved by said decompression element using a look-up table stored within said memory element. 
     
     
       25. The modem receiver according to claim 22, further comprising: a de-rotation element, in communication with said receiver element, for rotating the received, demodulated parallel signal set to a received parallel data set;   a de-emphasis element, in communication with said de-rotation element, for providing non-linear de-emphasis attenuation to said received parallel data set, said non-linear de-emphasis attenuation applied to an uneven distribution of bits among each of a plurality of parallel data sub-bands to provide a de-emphasized parallel data set; and   a rotation element, in communication with said de-emphasis element, for rotating said de-emphasized parallel data set into a de-emphasized parallel signal set and for providing said de-emphasized parallel signal set to said decompression element.   
     
     
       26. The modem receiver according to claim 15, wherein said demodulator is an FM demodulator. 
     
     
       27. The modem receiver according to claim 26, wherein said FM demodulator further comprises a zero-crossing counter in lieu of an analog-to-digital converter. 
     
     
       28. The modem receiver according to claim 15, wherein said demodulator is an AM demodulator. 
     
     
       29. The modem receiver according to claim 16, wherein said de-rotation matrix applied by said inverse rotation element is adaptively adjustable to compensate for frequency-dependent distortion in said modulated signal, resulting in adaptive de-rotation of the plurality of mutually-orthogonal signal coordinates. 
     
     
       30. A modem for communicating serial input data as a signal over a transmission link and for providing serial output data substantially equivalent to said serial input data, said modem comprising: a partitioning element for receiving and partitioning said serial input data into a parallel data set;   a rotation element, comprising a rotation matrix, for providing an invertible, linear conversion of said parallel data set into a parallel signal set;   a modulator, in communication with said rotation element, for modulating a carrier with said parallel signal set;   a transmitter element, in communication with said modulator, for transmitting said modulated carrier as the signal over said transmission link;   a receiver element, in communication with said transmission link, for receiving said modulated carrier from said transmission link;   a demodulator, in communication with said receiver element, for demodulating a demodulated parallel signal set from said modulated carrier;   an inverse rotation element, comprising a derotation matrix in communication with said demodulator, for receiving said demodulated parallel signal set from said demodulator, and for providing an invertible, linear conversion of said parallel signal set into a parallel data set; and   an assembly element for receiving and assembling said parallel data set into said serial output data.   
     
     
       31. The modem according to claim 30, wherein said rotation and de-rotation matrices are commuting matrices. 
     
     
       32. The modem according to claim 30, wherein said rotation matrix further comprises a filter bank polyphase rotation matrix, said rotation element applying said polyphase rotation matrix to said parallel data set to produce said parallel signal set, and   said de-rotation matrix further comprises a filter bank polyphase de-rotation matrix, said inverse rotation element applying said polyphase de-rotation matrix to said received parallel signal set to produce said received parallel data set.   
     
     
       33. The modem according to claim 32, wherein said filter bank polyphase rotation matrix further comprises a multi-rate wavelet synthesizer filter-bank, said rotation element applying said multi-rate wavelet synthesizer filter-bank to said parallel data set to produce said parallel signal set, and   said filter bank polyphase de-rotation matrix further comprises an inverse multi-rate wavelet synthesizer filter-bank, said inverse rotation element applying said inverse multi-rate wavelet synthesizer filter-bank to said received parallel signal set to produce said received parallel data set.   
     
     
       34. The modem according to claim 30, further comprising: a pre-emphasis element, in communication with said partitioning element, for providing non-linear pre-emphasis amplification of said parallel data set prior to introduction of said parallel data set into said rotation element; and   a de-emphasis element, in communication with said inverse rotation element, for providing non-linear de-emphasis attenuation of said parallel data set prior to introduction of said parallel data set into said assembling element.   
     
     
       35. The modem according to claim 30, further comprising: a compression element, in communication with said rotation element, for providing non-linear, logarithmic amplification of said parallel signal set prior to introduction of said parallel signal set into said modulator; and   a decompression element, in communication with said inverse rotation element, for providing non-linear, logarithmic attenuation of said received parallel signal set from said receiver element.   
     
     
       36. The modem according to claim 30, wherein said modulator is an FM modulator, and   said demodulator is an FM demodulator.   
     
     
       37. A method of transmitting and receiving serial data over a transmission link comprising: partitioning said serial data into a parallel data elements;   applying a rotation operator to said parallel data elements to form parallel signal elements, wherein said rotation operator comprises a geometric rotation matrix, said parallel data elements comprise coordinates of a vector in a first coordinate system, and said parallel signal elements comprise coordinates of a vector in a second coordinate system;   modulating a carrier with said parallel signal elements;   transmitting said modulated carrier over said transmission link;   receiving said modulated carrier from said transmission link;   demodulating said modulated carrier into received parallel signal elements;   applying an inverse rotation operator to said received parallel signal elements to form received parallel data elements; and   assembling said received parallel data elements into said serial data.   
     
     
       38. The method according to claim 37, wherein said step of partitioning further comprises assigning an unequal number of bits from said serial data to each of said parallel data elements. 
     
     
       39. The method according to claim 38, wherein said step of assembling further comprises selecting the same number of bits from each of said parallel data elements as employed in said partitioning step in forming said serial data. 
     
     
       40. The method according to claim 38, wherein said step of partitioning further comprises assigning bit representation levels for each of said parallel data elements according to a number of bits assigned to the parallel data element. 
     
     
       41. The method according to claim 40, wherein said step of assembling comprises comparing and resolving perceived bit levels within each of said parallel data elements to said bit representation levels employed in said partitioning step. 
     
     
       42. The method according to claim 37, wherein said step of applying a rotation operator further comprises applying said parallel data elements to a filter bank polyphase rotation matrix to provide said parallel signal elements. 
     
     
       43. The method according to claim 42, wherein said step of applying said filter bank polyphase rotation matrix further comprises applying said parallel data elements to a multi-rate wavelet filter bank to provide said parallel signal elements. 
     
     
       44. The method according to claim 37, wherein said step of applying an inverse rotation operator further comprises applying an inverse rotation operator which commutes with said rotation operator. 
     
     
       45. The method according to claim 37 further comprising the step of compression amplifying said parallel signal elements prior to modulating a carrier with said parallel signal elements. 
     
     
       46. The method according to claim 45 further comprising the step of decompression attenuating said received parallel signal elements prior to said step of applying an inverse rotation operator, wherein said decompression attenuation is an inverse operation to said compression amplification. 
     
     
       47. The method according to claim 46, wherein said steps of compression amplification and decompression attenuation further comprise mu-law amplification and mu-law attenuation, respectively. 
     
     
       48. The method according to claim 37, wherein said step of applying an inverse rotation operator further comprises adaptively equalizing said inverse rotation operator prior to applying said inverse rotation operator to said received parallel signal elements thus achieving adaptive equalization of frequency-dependent distortion in said transmitted modulated carrier. 
     
     
       49. A method of sending data from a first modem coupled to a first end of a wireless transmission link to a second modem coupled to a second end of said wireless transmission link, each of said first and second modems including a modulator and a demodulator, said method comprising the steps of: inputting a data sample to each of a plurality of channels of said modulator of said first modem;   forming an input data frame from said plurality of input data samples;   multiplying said input data frame by a first rotation matrix to provide an output data frame, wherein said first rotation matrix is provided having a row dimension and a column dimension corresponding to said number of channels in said modulator of said first modem;   frequency modulating a carrier signal with said output data frame;   transmitting said frequency modulated signal over said transmission link;   receiving said transmitted frequency modulated signal in a demodulator having a plurality of channels;   frequency demodulating said frequency modulated signal to recover a received data frame; and   multiplying said received data frame by a second rotation matrix to provide an output data frame, wherein said second rotation matrix is provided having a row dimension and a column dimension corresponding to a number of channels in said demodulator and wherein multiplication of said received data frame by said second rotation matrix results in an output data frame corresponding to said input data frame.   
     
     
       50. The method of claim 49 wherein said modulator and demodulator are provided having a like plurality of channels. 
     
     
       51. The method of claim 49 wherein: said step of multiplying by a first rotation matrix comprises applying said input data frame to a first finite response filter; and   said step of multiplying by a second rotation matrix comprises applying said received data frame to a second finite response filter which operates as an inverse, commuting operator to said first finite response filter.   
     
     
       52. A modem transmitter for communicating serial input data as a signal over a transmission link, said modem transmitter comprising: a partitioning element for receiving and partitioning said serial input data into a parallel data set;   a rotation element, comprising a multi-rate wavelet synthesizer filter-bank in communication with said partitioning element, for providing an invertible, linear conversion of said parallel data set into a parallel signal set;   a modulator, in communication with said rotation element, for modulating a carrier with said parallel signal set; and   a transmitter element, in communication with said modulator, for transmitting said modulated carrier as said signal over said transmission link, wherein said parallel data set is a plurality of data coordinates,   said parallel signal set is a plurality of signal coordinates, and   said rotation element is operative for applying said multi-rate wavelet synthesizer filter-bank to said plurality of data coordinates to produce said plurality of signal coordinates.